Allow ignoring undefined attributes during unmarshalling

.changelog/213.txt

@@ -0,0 +1,7 @@
+```release-note:enhancement
+tfprotov5/state: Added `UnmarshalWithOpts` func to facilitate configurable behaviour during unmarshalling
+```
+
+```release-note:enhancement
+tfprotov6/state: Added `UnmarshalWithOpts` func to facilitate configurable behaviour during unmarshalling
+```

tfprotov5/state.go

@@ -77,3 +77,22 @@ func (s RawState) Unmarshal(typ tftypes.Type) (tftypes.Value, error) {
 	}
 	return tftypes.Value{}, ErrUnknownRawStateType
 }
+
+// UnmarshalOpts contains options that can be used to modify the behaviour when
+// unmarshalling. Currently, this only contains a struct for opts for JSON but
+// could have a field for Flatmap in the future.
+type UnmarshalOpts struct {
+	ValueFromJSONOpts tftypes.ValueFromJSONOpts
+}
+
+// UnmarshalWithOpts is identical to Unmarshal but also accepts a tftypes.UnmarshalOpts which contains
+// options that can be used to modify the behaviour when unmarshalling JSON or Flatmap.
+func (s RawState) UnmarshalWithOpts(typ tftypes.Type, opts UnmarshalOpts) (tftypes.Value, error) {
+	if s.JSON != nil {
+		return tftypes.ValueFromJSONWithOpts(s.JSON, typ, opts.ValueFromJSONOpts) //nolint:staticcheck
+	}
+	if s.Flatmap != nil {
+		return tftypes.Value{}, fmt.Errorf("flatmap states cannot be unmarshaled, only states written by Terraform 0.12 and higher can be unmarshaled")
+	}
+	return tftypes.Value{}, ErrUnknownRawStateType
+}

tfprotov5/state_test.go

@@ -0,0 +1,83 @@
+package tfprotov5_test
+
+import (
+	"math/big"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+
+	"github.com/hashicorp/terraform-plugin-go/tfprotov5"
+	"github.com/hashicorp/terraform-plugin-go/tftypes"
+)
+
+func TestRawStateUnmarshalWithOpts(t *testing.T) {
+	t.Parallel()
+	type testCase struct {
+		rawState tfprotov5.RawState
+		value    tftypes.Value
+		typ      tftypes.Type
+		opts     tfprotov5.UnmarshalOpts
+	}
+	tests := map[string]testCase{
+		"object-of-bool-number": {
+			rawState: tfprotov5.RawState{
+				JSON: []byte(`{"bool":true,"number":0}`),
+			},
+			value: tftypes.NewValue(tftypes.Object{
+				AttributeTypes: map[string]tftypes.Type{
+					"bool":   tftypes.Bool,
+					"number": tftypes.Number,
+				},
+			}, map[string]tftypes.Value{
+				"bool":   tftypes.NewValue(tftypes.Bool, true),
+				"number": tftypes.NewValue(tftypes.Number, big.NewFloat(0)),
+			}),
+			typ: tftypes.Object{
+				AttributeTypes: map[string]tftypes.Type{
+					"bool":   tftypes.Bool,
+					"number": tftypes.Number,
+				},
+			},
+		},
+		"object-with-missing-attribute": {
+			rawState: tfprotov5.RawState{
+				JSON: []byte(`{"bool":true,"number":0,"unknown":"whatever"}`),
+			},
+			value: tftypes.NewValue(tftypes.Object{
+				AttributeTypes: map[string]tftypes.Type{
+					"bool":   tftypes.Bool,
+					"number": tftypes.Number,
+				},
+			}, map[string]tftypes.Value{
+				"bool":   tftypes.NewValue(tftypes.Bool, true),
+				"number": tftypes.NewValue(tftypes.Number, big.NewFloat(0)),
+			}),
+			typ: tftypes.Object{
+				AttributeTypes: map[string]tftypes.Type{
+					"bool":   tftypes.Bool,
+					"number": tftypes.Number,
+				},
+			},
+			opts: tfprotov5.UnmarshalOpts{
+				ValueFromJSONOpts: tftypes.ValueFromJSONOpts{
+					IgnoreUndefinedAttributes: true,
+				},
+			},
+		},
+	}
+	for name, test := range tests {
+		name, test := name, test
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			val, err := test.rawState.UnmarshalWithOpts(test.typ, test.opts)
+			if err != nil {
+				t.Fatalf("unexpected error unmarshaling: %s", err)
+			}
+
+			if diff := cmp.Diff(test.value, val); diff != "" {
+				t.Errorf("Unexpected results (-wanted +got): %s", diff)
+			}
+		})
+	}
+}

tfprotov6/state.go

@@ -77,3 +77,22 @@ func (s RawState) Unmarshal(typ tftypes.Type) (tftypes.Value, error) {
 	}
 	return tftypes.Value{}, ErrUnknownRawStateType
 }
+
+// UnmarshalOpts contains options that can be used to modify the behaviour when
+// unmarshalling. Currently, this only contains a struct for opts for JSON but
+// could have a field for Flatmap in the future.
+type UnmarshalOpts struct {
+	ValueFromJSONOpts tftypes.ValueFromJSONOpts
+}
+
+// UnmarshalWithOpts is identical to Unmarshal but also accepts a tftypes.UnmarshalOpts which contains
+// options that can be used to modify the behaviour when unmarshalling JSON or Flatmap.
+func (s RawState) UnmarshalWithOpts(typ tftypes.Type, opts UnmarshalOpts) (tftypes.Value, error) {
+	if s.JSON != nil {
+		return tftypes.ValueFromJSONWithOpts(s.JSON, typ, opts.ValueFromJSONOpts) //nolint:staticcheck
+	}
+	if s.Flatmap != nil {
+		return tftypes.Value{}, fmt.Errorf("flatmap states cannot be unmarshaled, only states written by Terraform 0.12 and higher can be unmarshaled")
+	}
+	return tftypes.Value{}, ErrUnknownRawStateType
+}

tfprotov6/state_test.go

@@ -0,0 +1,83 @@
+package tfprotov6_test
+
+import (
+	"math/big"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+
+	"github.com/hashicorp/terraform-plugin-go/tfprotov6"
+	"github.com/hashicorp/terraform-plugin-go/tftypes"
+)
+
+func TestRawStateUnmarshalWithOpts(t *testing.T) {
+	t.Parallel()
+	type testCase struct {
+		rawState tfprotov6.RawState
+		value    tftypes.Value
+		typ      tftypes.Type
+		opts     tfprotov6.UnmarshalOpts
+	}
+	tests := map[string]testCase{
+		"object-of-bool-number": {
+			rawState: tfprotov6.RawState{
+				JSON: []byte(`{"bool":true,"number":0}`),
+			},
+			value: tftypes.NewValue(tftypes.Object{
+				AttributeTypes: map[string]tftypes.Type{
+					"bool":   tftypes.Bool,
+					"number": tftypes.Number,
+				},
+			}, map[string]tftypes.Value{
+				"bool":   tftypes.NewValue(tftypes.Bool, true),
+				"number": tftypes.NewValue(tftypes.Number, big.NewFloat(0)),
+			}),
+			typ: tftypes.Object{
+				AttributeTypes: map[string]tftypes.Type{
+					"bool":   tftypes.Bool,
+					"number": tftypes.Number,
+				},
+			},
+		},
+		"object-with-missing-attribute": {
+			rawState: tfprotov6.RawState{
+				JSON: []byte(`{"bool":true,"number":0,"unknown":"whatever"}`),
+			},
+			value: tftypes.NewValue(tftypes.Object{
+				AttributeTypes: map[string]tftypes.Type{
+					"bool":   tftypes.Bool,
+					"number": tftypes.Number,
+				},
+			}, map[string]tftypes.Value{
+				"bool":   tftypes.NewValue(tftypes.Bool, true),
+				"number": tftypes.NewValue(tftypes.Number, big.NewFloat(0)),
+			}),
+			typ: tftypes.Object{
+				AttributeTypes: map[string]tftypes.Type{
+					"bool":   tftypes.Bool,
+					"number": tftypes.Number,
+				},
+			},
+			opts: tfprotov6.UnmarshalOpts{
+				ValueFromJSONOpts: tftypes.ValueFromJSONOpts{
+					IgnoreUndefinedAttributes: true,
+				},
+			},
+		},
+	}
+	for name, test := range tests {
+		name, test := name, test
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			val, err := test.rawState.UnmarshalWithOpts(test.typ, test.opts)
+			if err != nil {
+				t.Fatalf("unexpected error unmarshaling: %s", err)
+			}
+
+			if diff := cmp.Diff(test.value, val); diff != "" {
+				t.Errorf("Unexpected results (-wanted +got): %s", diff)
+			}
+		})
+	}
+}